One of the most difficult problems for an amputee is obtaining a prosthesis, i.e., an artificial arm or leg, which can be worn comfortably over a long period of time. The process of making an artificial limb is quite time consuming and involves a considerable amount of fitting and adjusting. The prosthesis must be carefully fitted to the amputess residual limb, and it must be adjusted in its design to keep the weight off of the pressure-sensitive areas while permitting dynamic movement of the prosthesis and a firm attachment to the residual limb. Moreover, the residual limb varies in shape and size over a period of time because of shrinking and swelling. Size changes are common and may be caused by many factors, including heat, retention of body fluids and weight gain or loss.
Various suggestions have been made to accommodate size and shape changes and to improve the comfort of the amputee. U.S. Pat. No. 1,057,562 discloses an inflatable wrap around sleeve placed between a pair of stump socks and providing a cushion between the residual limb and the shell of the prosthesis. U.S. Pat. No. 2,634,424 discloses an inflatable socket having a series of interconnected communicating compartments. Similar inflatable sockets are shown in U.S. Pat. Nos. 3,889,301 and 4,300,245. U.S. Pat. No. 1,893,853 shows an inflatable tube mounted in the wall of the socket acting against the fabric sleeve covering the residual limb, and U.S. Pat. No. 4,655,779 discloses an inflatable socket which is inflated by means of a finger pump.
The problem with each of these prior art devices is that while they do provide an air cushion, they do not provide for the adjustment of pressure precisely where it is needed by the amputee in order to achieve the greatest degree of comfort and yet obtain completely stable and firm attachment of the prosthesis to the residual limb.